The eye

Question 1

What is the function of the optic nerve?

Answer 1

Carries electrical impulses from the retina to the brain

Question 2

What is the blind spot?

Answer 2

The point on the retina where the optic nerve leaves the eye; thus no receptors are located there

Question 3

What is the function of the retina?

Answer 3

A light sensitive layer which send impulses to the optic nerve

Where the image is formed at the back of the eye

Question 4

What is the function of the lens?

Answer 4

The lens changes shape to focus light on the retina.

Question 5

What is the function of the choroid?

Answer 5

A pigmented layer which absorbs light to prevent reflection
Also contains blood vessels to nourish the retina

Question 6

What is the function of the sclera?

Answer 6

A protective, tough white outer coat

Question 7

What is the function of the iris?

Answer 7

Muscles that alter the pupil size to control the amount of light entering

Question 8

What is the function of the pupil?

Answer 8

A hole in the centre of the iris which allows light to enter

Question 9

Why do the pupils constrict in bright light?

Answer 9

In bright light the iris muscles contract to make the pupils smaller, preventing excess light from entering and damaging the retina

Question 10

Why do pupils dilate in dim light?

Answer 10

Under low light intensities, the iris muscles contract to make the pupil larger, to allow more light to enter the eye